Controlling device for two-stage compressors.



R. CONRADER. GONTROLLING DEVICE FOR TWO STAGE GOMPRESSORS.

APPLIUATION FILED JAN. 24,

RUDOLPH (IONRADER, OF ERIE, PENN SYLVANI.

CONTROLLING DEVICE FOR TWO-STAGE GOMPRESSOBS.

Speciication. of Letters Patent.

Patented May 18, 1909.

Application led January 24, 190e. Serial No. 297,595.4

To all 'whom it may concern: l

Be it known thatI I, RUDOLPH CONRADER, a citizen ot the United States, residing at Erie, in the count-y ot' Erie and State of Pennsylvania, have invented new and' useful -Improvemeits in Controlling Devices for Two-Stage Compressors, Aof which the following is a specification.

This invention relates to controlling devices for twostage compressors, and consists in certain improvements in theconstruction thereof as Will be hereinafter fully described and pointed out in the claims.

The main object of the invention is to prevent the development of an excess of heat at the discharge ofthe high pressure cylinder. 'It has been found that in tivo stage compressors or compressors having a plural-ity of cylinders in which the relieving A device is arranged on the intake of the low pressure cylinder, that under certainconditions, practically the same amount of heat is developed at the discharge of the high pressure cylinder as lwould he developed in effecting the compression with a singlestage compressor. Inasmuch as compressors are often used in mines and other places Where such excessive heat is likely to cause explosions, the prevention of this becomes of great importance for such compressors.-

T he invention is illustratedin the accompanying drawings as follows: Figure l shows a cross section ot' a4 two stage compresser, with my devices thereon. Fig. 2 shows a detail view4 of the frame of the relietl device for the low pressure cylinder. 'Fig 3 is an enlarged view of the actuated mechanism for the regulator of -the high pressure cylinder. Fig. 4 shows a. side elevation of the frame of said regulating device.

A'marks the lower pressure cylinder, B the high pressure cylinder, a the intake of the low pressure cylinder, b the inta-ke'oil the high pressure cylinder, a the' discharge of vthe low pressure cylinder and b the discharge of the high pressure cylinder. The lovv pressure cylinder discharges into an intermediate -cooler C. This cooler comprises the shell c, the partition plate c arranged on this shell, the connecting tubes c2 extending from one plate to the other, the heads c secured on the partition plates forming the chamber c3, and the vinlet c4 and outlet c5.

The cooling medium is admitted at c4, Ipassing from the chamber c3 through the tube c2 to the outlet chamber c3, and through the discharge `tubes c5, The air isl cooled by contact With the tubes 021 y Ordinarily the cylinders A and B are so proportioned that operatin normally the high pressure cylinder Wil discharge exactly the same amount of air as is compressed by the low pressure cylinder. O'f i course, the volume under the higher coinpression is less. l

I prefer to provide the low pressure cylinder with a relieving device similar to that.

shown by me in Patent No. 775,393 dated November 22, `1904. This relieving device D has the valve chamber d, in which there is the partition d. The valve d? is of the'. throttling type, having the' closure disks fl d3, and connecting Web ai, a stem d6 extending from this` valve and connected with' a piston D. The -piston is arranged in a c linder4 D2. The cylinder 1s carried by a t ame D5 secured to the Walls of the valve chamber d. The upper end of the cylinder communicates with an air chamber ZT and a passage il connecting this chamber with a cylinder Dt. The needle valve (ls controls this passage., The needle valve is is carried by .the piston D3, the piston being arranged in the cylinder D4. A stem d10 extends from the piston and engages the arm of the bell crank lever du. The other arm d of the bell crank lever has the weight d adjustably arranged upon it. A spring d is secured to the cylinder D1L and to the bell cranklever by means of eye bolt d1 and adjusting nut (ZU. By means of the adjusting nut and the adjustable weight any pressure desired may be put upon the piston D3, so that the piston can be made to oper ate at any desired minimum pressure. minute vent d1 leads from air chamber di. IVith ,the initial opening of the passage (Z9 by the valve (Z8,'tl1is vent permits a certain amount of air to escape. The size of the passage d relatively to this vent is such, however, that when the valve is fully open. practically receiver pressure is maintained in the chamber a7, so that the change of pressure in the chamber (l and cylinder D2 is very much in excess ot' the chaiige of pressurel in the receiver. In other Words, the change of pressure in the receiver is intensified in this device so that very close regulation may be maintained. This mechanism is not new in this instance, as it was shown in my former patent. A cross head is arranged in the partition.

the spring cl2. `The d is attached to the stem fil and springs are tensioned between said cross head and s therarm r. and the end of the cylinder. These tend to open the valve l and to maintain it in an open position until the receiver pressure exceeds the desired minimum, The valve is then moved so as to reduce the amount of air permitted to enter through the intake, and the pressure continues the increase eventually entirely closesA it. l pre'- fer, however, that this valve act as a regt# ulator, that is, that it does notxgo entirely from a closed to an open position, but its movement is graduated to open to supply the amount. of air required, as was more fully -set forth in my former patent.

It will be observed that if the`relief device D is actuated with no other controlling device for the entire compressor, that the low pressure cylinder A Will discharge a less amount of air than will be pumped by the high pressure cylinder, so that the pressure in the intermediate cooler C Will gradually decrease. Eventually, if the supply drawn from the receiver happens to be such as to actuate the relief device D to pump only a very small amount of air, then theV pressure of the air at the intake of the high pressure cylinder will be simply atmospheric pressure. Indeed the conditions may be such as to make it less than this, but still deliver some air. The result of this is that the high pressure cylinder alone boosts the pressure from that of the atmosphere, or less than atmospheric pressure, to the full receiver pressure, and this creates the dangerous amount of heat heretofore referred to. To prevent this, I provide the regulating device It comprises the valve chamber e, in which is arranged the diaphragm e. The pipe b2 connects the cooler C With the chamber. The valve e2 of the throttling type It has the closure disks e3 c, and the connecting webs e2 as usual in the balanced throttling type of the valve. A stem c extends from this valve and is connected with a piston E. This 'iston operates in a cylinder the cylin er beingl carried by a frame E mounted on the valve chamber. f The cylinder E2 is connected with an air chamber e7 and this air chamber is connected by a'passage e9' The valve e1 controls` It is carried by the piston ena with a cylinder E4. this passage.

The piston is subjected to the pressure of pressure of the spring may be adjusted by the mit e. 'A passage e through the nut prevents the trapping of air back of the piston. The cylinder E4 is connected by a pipe b3 with the ipe b2, and consequently with the cooler (i) The air chamber c7 is provided with a vent es to permit the escape of the air from the cylinder E2. Springs E5 are tensioned between the cross heads el and the arm e1C on the'cylinder EL. In thisv device, the spring tends to or closes the valve while the. air pressure operal ing' on the piston E tends to or opens the valve. ln this construction. l. prefer that the valve el" be so constructed and the vent es be so proportioned to the passage e that practically full cooler pressure is delivered 'to-the cylinder E: with the initial opening of the valve W.'- lfher't'he parte; a. e .so arranged, the"vcnt simply acts as a lea k to -dispose of the air in the cylinder. When the cooler pressure is normal, it is sufficient to actuate the piston cu to Open the Vvalve c1U and to maintain the valve in this position.

The air acting on the piston E', with these conditions, therefore, maintains the valve c2 in an open position. Under these conditions,

the high pressure cylinder simply boosts the pressure from the normal coolerpressine to'the receiver pressure. rdinarily7 the cooler pressure is mid-way between atmospheric pressure`and receiver pressure, and

under these conditions, the excessive heat avoided. lVhen, however, the supply taken from the receiver isso small as to require but a small .part of the capacity of the pump, the relief device D acting upon the low pressure cylinder, so reduces the amount discharged by this cylinder, to the cooler, that the cooler pressure falls. The -regulating device lf may be so adjusted by means of' the'scrow-e15 that when the cooler pressure reaches a dangerous pre-determined minimum, it will overcome the an' pressure act-ing upon the piston e, and will close the valve e1". The vent es will allow the leakage of trapped air from the cylinder IP and the spring will entirely close the valve et. vrlhe high pressure cylinder will then'inimediately discharge itself, with the exception of the clearance, and will continue to operate in ar partial vacuum and will cease, to discharge air, so that no further heat will be developed. lVhen the air pressure in the cooler has been raised above the pre-determined minimum, this pressure acts upon the piston e opening'the valve @1 and operates as before describe`d, opening' the valve 92, and air `of the normal cooler pressure is again admitted to the high pres; sure cylinder. In the drawings, the pipe (i which is connected with the discharge 7, may be considered as the receiver, and the pipe F connects the receiver with the cylinder D4 of the relief device D.

What I claim as new is: l l. In a controlling device for two stage compressors, the combination of the low and high pressure cylinders; an intervening cooler; a relief device for the low pressure vcylinder-acting independently of the cooler,

and actuated by the pumped fluid; and a regulating device controlling the action of the high pressure cylinder to maintain a minimum pressure in the cooler.

CIJ

.il l) lOO' andf controlling the volume of fluid discharged by said high pressure cylinder; and a rellef device for the low pressure cylinder, cont-rolled by the pressure of the pumped fluid and acting upon the intake of'said low pressure cylinder.

3. In controlling devices for two stage coi pressors the combination with the low au high pressure cylinders; of a regulating device for the high pressure cylinder controlled by thel pressure between the cylinders,

and controlling the volume of iiuid discharged by said high pressure cylinder to control the action of the high pressure cylini, der to decrease the discharge therefrom when thek pressure between the cylinders reaches a pre-determined minimum; and a relief device for thelow'pres'sure cylinder controlled by the pressure of the pumped Huid and acting upon the intake of said low pressure cylinder.

4. In controlling devices for two stage compressors the combination with the low and high pressure cylinders; of a regulating device for the high pressure cylinder, controlled by pressure betweenthe cylinders, and controlling the volume of fluid discharged by said high pressure cylinder, said regulating device being arranged to act on the intake of saidhigh pressure cylinder; and a relidevice for the low' pressure cylinder controlled by the 'pressure of the pumped iiuid and acting upon theintake of said low pressure cylinder. 4.

In controlling devices for two stage compressors the combination with the low and high pressure cylinders; of a regulating device forthe high pressure cylinder, controlled by pressure between the cylinders, and controlling the volume of fluid discharged by said high pressure cylinder; and a relief device for the low pressure cylinder controlled by the-pumped fluid and acting on the intake of said low pressure cylinder, said relic-f device being arranged to graduate the chargepumped by the low pressure cylinder as the pressure of the pumped fluid changes. v

6. In controlling devices for two stage compressors the combination withthe lowv and high pressure cylinders; an intermediate cooler and a regulating device acting on the intake of the high pressure cylinder for maintaining pressure in the -cooler and adapted to close abruptly when the cooler pressure falls below a predetermined minimum; and a relief device actuated by' the pumped fluid in the low pressure cylinder, lsaid relief device being arranged on the intake of said low pressure cylinder.

7. In cont-rolling devicesfor two stage compressors the combination with the low and high pressure cylinders; and an intermediate cooler between said cylinders; of a relief device acting on the intake of the low` pressure cylinder and actuated by the pumped fiuid; and a regulating device controlling the action of the high pressure cylinder to' maintain a minimum pressure in the cooler.

In testimony whereof I have hereunto set my hand in the presence of two subscribing witnesses. y

RUDOLPH CONRADER. "Witnesses:

' H. C. LORD,

4Bassin F. PARKER. 

